1. Field of Invention
The present invention relates to extenders or covers fitted over electrical terminal blocks in electrical power distribution equipment.
2. Description of Prior Art
Terminal blocks have long been widely used in electrical utilities, serving as electrical connectors for electrical current power supplies and the like used in relaying, intercommunication and other signalling within power grids. Terminal blocks also have been used as connectors for relatively low voltage electrical power. Terminal blocks have been desirable because they facilitated assembly, installation and connection of electrical instruments and connectors. Further, there was no need to use splicing or soldering between individual conductors.
Terminal blocks have generally been designed to maximize their compactness. This was done to minimize the space required for them as well as for increased strength and lack of susceptibility to voltage breakdown.
An example prior art terminal block is of the type in U.S. Pat. No. 3,067,403. Other electrical terminal blocks are set forth in U.S. Pat. Nos. 2,923,913; 3,275,972; 3,247,480; 2,411,014; 4,697,720 and 4,637,676. Emphasis on compactness has caused certain problems. For example, sets of contacts carrying electricity at different polarities, phases or voltages were located adjacent each other. Even if care was taken, there was still a risk of misconnecting contacts of different potentials or polarities. This could cause arcing, fire or other problems. Although some terminal blocks had ribs or partition walls between electrical contacts, the risk of misconnection and the problems which could be caused were still of concern.